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1970 mustang 351w Utah
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Discussion Starter #1
So I recently bought a 70 coupe with the 351w. It has the stock 2 barrel on it. It has been sitting for 7 years. Did compression on it. 1 cylinder was at 110, 5 were at 100, 1 was at 80 and 1 was at 50. I am trying to do this on a semi budget. I am planning on intake, 4 barrel, cam and lifters already. I am also planning on having the heads gone through. I have been looking at edelbrock. I can get it cheaper through work. Any thing else and recommendations.
 

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1969 Mustang Coupe 302/331
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The one at 50 will always be a problem, the one at 80 will hold you back from ever getting full power but more important.....are you sure you did the compression the same for each cylinder ? I do it again to be sure.
Measure twice, cut once is the rule.
If you going to rebuild the top end you might as well fix the bottom.
Just my 2 cents.
 

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1970 mustang 351w Utah
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Discussion Starter #3
I am hoping cylinder walls are good and I can just replace the piston rings.
 

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You need to find out whats going on with those 2 cylinders. You should have no more than 20 psi difference between the best and worst cylinders. Maybe a ring is stuck because it was sitting so long? Could be some rust inside the questionable cylinders? Could also have an issue with the valves/seats leaking? I'd stick with your plan and pull the heads and oil pan to have a look-see.
 

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1970 mustang 351w Utah
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Discussion Starter #5
Will do. It is currently 20 miles from. Home. Should I drive it? Is m worried about a broken ring gouging the cylinder wall.
 

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I've always followed the premise, one should insure, in this case, the engine is in good working order, before any modifications are considered. Otherwise, it's just lipstick on a pig. Tear it down and check it out.....
 

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The possibility always exists with something so old and unknown that, upon disassembly, you'll find that the condition of the cylinders and the overbore required to make them serviceable again (taper and centricity) will exceed the maximum allowable cylinder diameter, meaning the block will be unusable without cylinder sleeve(s). A disassembly and measurement of all specifications.. cylinder bore, taper, centricity (roundness), ridge, defects, crankshaft journal diameter, taper and centricity, connecting rod straightness, cylinder head inspection (valve guide diameter, seat condition, etc. and the condition of all threaded holes/bosses and only THEN can you calculate what will be needed.
 

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The possibility always exists with something so old and unknown that, upon disassembly, you'll find that the condition of the cylinders and the overbore required to make them serviceable again (taper and centricity) will exceed the maximum allowable cylinder diameter, meaning the block will be unusable without cylinder sleeve(s). A disassembly and measurement of all specifications.. cylinder bore, taper, centricity (roundness), ridge, defects, crankshaft journal diameter, taper and centricity, connecting rod straightness, cylinder head inspection (valve guide diameter, seat condition, etc. and the condition of all threaded holes/bosses and only THEN can you calculate what will be needed.
Woodchuck is right...and you shouldn't hope you should verify. I have fairly well but backyard rebuilt 302 that comes in at 150 PSI squarely on all cylinders. Hot vs cold will ready different 120 vs 150. That's what a good engine should look like. While it's possible your valvetrain is the root cause your cylinders are probably not much better.

I'm not trying to make a buck but I am eventually going to sell it. I have a complete cylinder bore measuring micrometer kit. Brand new used once. Used it on my VIN matching 289 not the running 302 to measure wear. It was extremely accurate and I found that my orig an unrebuilt motor was less than 0.010 to spec except at the very top of cyl before the ridge where it mushroomed out to about a little more than .0150 - .020 out. The book will tell you exactly how much deviation is allowed outside the starting measurement. I measured the lower part of my bores (which you can't do w/o pistons removed as I have done on the 289) where the piston does not travel to verify my instrument and the way I was measuring was on target for accuracy to the book spec and it was dead accurate. This is how you can verify cylinder condition. With each piston at BDC you can measure the middle and top of bores which is where most wear occurs. It was a one time use purchase which is why I'm going to sell the kit....maybe. but I think the mic and tool cost me about 75$ bucks on Amazon.
 

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I'd make it run before tearing down...its been sitting 7 years. But that is just me. If it's hurt, you will know. But after sitting so long...I would want some heat and oil to run through it to get things moving again. I did not read that you had fired this motor at all, but i could be wrong...sometimes you got to figure out why the last guy parked it for 7 years...

I would not drive it more than a few blocks to verify motor, trans shifting, and brakes work properly.
 

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1970 mustang 351w Utah
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Discussion Starter #10
I got it running drove about 5 miles. Then did compression test a few days later. I found a rebuilt block for 1k. I am thinking about buying it.
 

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Lots of good advice here. I agree put a couple hundred miles on it and recheck. Could very well have stuck rings not sealing. However the reality is the car is 50. years old. Who knows how many miles on the motor or what shape it's really in. These older motors wore the cylinder wall quite a bit due to various reasons and just dog tired.

Another option is to pick up a 80's-90's truck 351W. Due to lower tension piston rings and EFI that doesn't wash down the cylinder walls with excess fuel, the cylinder walls hold up much, much better. Even a 150K mile motor will be in good shape. Plus a lot of them are roller cam. You probably could just install aftermarket heads and be good to go.
 
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